Scout out a location for your compost bins in your yard. The area should be out of direct sunlight but still have access to rainfall. A location close to the garden will make it easier to add garden waste and spent plants to the compost bins.
Lay the wood pallets out in the approximate design of the compost bins. This design is basically three connected boxes with the sides of each box one pallet wide.
Build the first box. Stand up two pallets on their end in an "L" shape with the edges touching. Thread a zip tie through the holes closest to the connected edges at both the top and the bottom. Pull and fasten tightly to connect the two pallets together. Build the other two sides of the box in the same manner until all sides are connected together. Leave the top and bottom of the box open.
Build the second box onto the first. Attach another pallet to form the back of the second box to the side pallet of the first box with zip ties at the top and bottom. The side of the first box will also act as one side of the second box so only three additional sides need to be erected.
Build the third box onto the second in the same manner as the first two boxes were connected. If the zip ties have been pulled tight, the boxes should not wobble.
Add materials to compost to the first box only until full, then leave that box alone and begin filling the second box. The compost in the first box will continue to compost down until finished. When the second box has been filled, begin adding to the third. Keep the boxes covered with a tarp if you have problems with raccoons and other animals raiding your compost. Remove the cover occasionally to allow rain to penetrate the compost piles.
Open a box to use the finished compost by cutting the zip ties that hold the front of the box to the sides. Remove the front and dig out the compost. When empty, return the front and re-attach with new zip ties.